The present invention relates to a sonotrode for generating an ultrasonic field in industrial production processes such as chemical processes or food-related processes, in which a liquid product is processed, which generates during the processing a foaming on the upper surface of the product. The invention relates also to a device comprising one or more such sonotrodes for de-foaming.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
In different fields of industry, the foam generation of a product to be processed is an inherent problem. In the field of beverage industry, for example, mainly with carbonated products such as cola and beer, but also with non-carbonated products such as fruit juices, etc., there exists during the production process, but also during the filling of the product into bottles or the like the problem that the product generates a large amount of foam. The generation of foam results often in an undesired loss of product, and also the contamination of the containers, into which the product is to be filled, is a big problem in these industries. During the filling process, the generation of too much foam leads to problems with regard to the sealing of the containers, and furthermore the filling line process is considerably slowed down due to the foam on top of the product. However, also in other industries, the foam generation of liquid products is a problematic issue. Examples of other industries are the chemical, petroleum, pharmaceutical and mining industries. Foam can form in tanks, open vessels or in containers or bottles, into which the product is filled. Due to the foam, there exists also a problem with regard to the vessel capacity/volume, the downstream processing equipment such as pumps, homogenizers, pasteurizers, filling lines and the filtration equipment.
In the prior art, conventional technologies used to reduce or to act against the generation of too much foam have for several years involved the use of anti-foam chemicals. However, in the food industry, the use of chemicals is not possible, and in other industries the use of such chemicals for reducing the generation of foam is rather cost-intensive. Also, the chemicals may change the characteristics of the liquid product, which is processed in the production line.
Furthermore, mechanical foam breakers have been suggested in the prior art in order to limit the generation of foam during the filling of beer or cola into bottles, for example. A further solution to this type of problem consists in anti-foam devices using ultrasound waves for the destruction of foam on top of the liquid product. In WO 2004/024317 A1, for example, an ultrasonic device is disclosed for eliminating the creation of foam in large containers. This known device uses round, plate-shaped resonators mounted on a rotating device and being provided with means for changing the angle of the treatment surface of the resonator plates of this device in the direction of the product. Through the change of the angle of the plate-shaped resonators and the rotation of the two devices, the ultrasonic field is focused on a specific spot on the surface of the product container. This system is rather big in its construction and difficult to be implemented in existing filling lines without substantial modifications. Furthermore, this known ultrasonic device needs complicated means for controlling the creation of the ultrasonic field and for permanent modifying the angle of radiation of the focused ultrasonic field.
In WO 2007/118285 A1, a further ultrasonic transducer system is disclosed, having a sonotrode with a main body part and a liquid treatment surface on its end. The foam treatment surface of this sonotrode is provided with a plurality of horn-shaped cavities. Due to the plurality of cavities, a more intensive ultrasonic field may be emitted. However, also this type of an ultrasonic treatment device has disadvantages in terms of the possibility to eliminate the generation of foam in certain applications, e.g. in filling lines for filling beverages into bottles or containers.
It would therefore be desirable and advantageous to provide a sonotrode and an ultrasonic device with at least one sonotrode, which are more efficient and more flexible with respect to the application in existing production lines and with respect to the foam elimination and foam reduction in different production processes.